Drip irrigation systems are used for providing a controlled flow of water for irrigation purposes. They typically comprise an irrigation pipe with outlet openings formed therein for the purpose of allowing outflows of water. In addition, drippers or emitters are typically provided within the pipe (in-line or integral drippers) or on the pipe (on-line drippers) in association with the outlet openings to ensure an appropriate drip rate of water therethrough.
In-line drippers typically comprise an inwardly facing surface, which faces the interior of the pipe, an outwardly facing surface, which faces the interior of the pipe, a circumferential wall, a water inlet, which is in fluid communication with the interior of the pipe, and a water outlet, which is in fluid communication with an outlet opening in the pipe. The inlet and outlet of the dripper may be connected by a meandering channel, which is often in the form of a flow-restricting labyrinth.
During manufacture of the pipe with the in-line drippers bonded to the interior thereof, the outlet openings must be formed in the pipe at a precise location with respect to the drippers. This requires determining the location of each dripper, and then forming the opening in a precise spot corresponding to the outlet of the dripper.
U.S. Pat. No. 6,039,270 (US '270) discloses a solution to overcome the necessity for determining the location of drippers during manufacture. In an irrigation pipe disclosed in US '270, the drippers comprise a cylindrical end-tube projecting from their outwardly facing surface, which is used as an outlet of the dripper. Each dripper is attached to the interior of the pipe so that it is swollen at the location of the end-tube, with the end-tube and the corresponding area of the pipe projecting from the swollen portion. The production line is provided with a stationary cutting plate located at a pre-determined height relative to the pipe, which cuts the projecting part of the pipe with the end-tube, thus forming the outlet opening in the pipe at the location of the end-tube, i.e., the dripper's outlet.